Malignant tumor (cancer) is one of the main diseases to seriously influence human health and threaten human life currently. More than 5 million people die of cancer all over the world every year. Even though there already have some therapeutic means such as surgery, radiotherapy, chemotherapy or the like, their cure rate is generally not high. At present, the chemotherapy mainly exsits some deficiencies such as poor selectivity, severe side effect and the like. Thus it is becoming one of the working focus of pharmacy operator every country to find antitumor medicament having lower toxicity, mild side effect, higher anticancer activity, good stability, etc.
It is reported that some purine derivatives have certain antiviral and antitumor activities. Please refer to relevant reports of EP 0353955, WO 9201968, JP10120682, KR9100441, etc.
Some substituted purine derivatives also are disclosed in prior art, for example, N6-disubstituted purin derivatives used for treating allergic diseases are disclosed in U.S. Pat. No. 4,853,386; 6-cyclopropylamino-9H-purine derivatives having antiviral activity are disclosed in JP2003-55377A and JP 2003-119197A. Glycosylated purin derivatives having anti-inflammatory effects are disclosed in J. Org. Chem. (pages 3212˜3215. vol. 69, 2004). N2-butylphenyl-2′-deoxy purin derivatives having activities of DNA α polymerase of eukaryotic cells are disclosed in J. Med. Chem. (pages 175˜181, vol. 27, 1984). 2,6,9-trisubstituted purin derivatives are disclosed in Tetrahedron Letters (1827˜1830, vol. 39, 1998). Further some compounds having antitumor effects are disclosed in the patent CN200510026846. It is a worthy attention to people to design N2,N6-disubstituted purin derivatives having better antitumor activity in further researches for filtering of antitumor activity of N2,N6-disubstituted purin compound.